1. Field of the Invention
This invention relates to folding knives and, more particularly, to a folding knife having a blade urged to the closed position and having a positive lock in the open position.
2. Description of the Prior Art
U.S. Pat. No. 220,438 (Slayton) discloses a combination razor and knife in which the blade includes a longitudinal slot. The housing for the blade includes a pin which extends through the slot and the blade is movable relative to the housing in two directions. The blade moves longitudinally by means of the slot and pin to lock the blade in the open position and in the closed position.
U.S. Pat. No. 338,853 (Marks) discloses a combination knife and fork element which utilizes a slot on the blade and a pin extending through a housing and disposed in the slot. The blade is accordingly movable relative to the housing by means of the slot. The housing also includes a slot extending inwardly from one edge, and the blade includes a stud which moves into the slot when the blade is folded into the housing to secure the blade into the housing.
U.S. Pat. No. 588,174 (Praunegger) discloses a folding knife, fork, or spoon apparatus which includes a longitudinal slot in one of the elements and a pin in the housing disposed in the slot. The blade is moved axially to lock the blade in the open position and also to lock the blade in the closed position.
U.S. Pat. No. 825,212 (Henkel) discloses a nail file utilizing a diagonally extending slot on the nail file blade and a pin on the housing. The blade is locked by moving the blade relative to the pin.
U.S. Pat. No. 2,183,901 (Weaver) discloses a pocket knife system utilizing a fixed pin and different slot arrangements. A pin extends through the various slots and is secured to the housing. Knife blades pivot on the pin and the knife blades are moved relative to the pin by means of the slots to lock the blades. Each blade, in addition to a slot, also includes a notch which cooperates with the pin and the blade in the locking environment.
U.S. Pat. No. 2,286,524 (Wilbur) discloses a springbiased locking arrangement for the folding blade of a pocket knife. A spring is used to bias elements into a locking relationship with a plurality of blades. The springbiased element is pulled outwardly against the bias of the spring in order to unlock the various blades to allow the blades to move.
U.S. Pat. No. 4,240,201 (Sawby et al) discloses a folding knife which utilizes a safety lock system which includes a plurality of cam elements and a bar spring.
U.S. Pat. No. 4,604,803 (Sawby) discloses another type of folding knife which utilizes a springbiased element to lock the blade. The springbiased element must be moved out of the way in order to fold the blade. The blade base, or the portion of the tang of the blade secured to the handle is moved laterally in order to free the blade from the cooperating locking elements.
All of the above-referenced patents include limitations of one form or another. In some apparatus, the blades may be moved inadvertently, and in other apparatus the actuation is relatively complicated because of the interconnection of the mechanical elements. The apparatus of the present invention overcomes the deficiencies of the prior art by providing a positive lock which requires a positive movement in order to move the knife blade from its open, use position to fold the knife blade into its closed position in the handle or case.